When a major incident takes place during the operating of a helicopter, it is necessary to proceed with the emergency evacuation of the aircraft.
If the helicopter doors are jammed and impossible to open, the passengers must exit the aircraft through the windows after having proceeded to release them.
Now, each window is connected to the aircraft structure by means of a frame. Typically, and as described in the document DE-A-673 951, this frame is made up:
of a joint comprising a central layer from which extends an external edge and an internal edge, the external edge being intended to be fixed onto the support and the lower edge being intended to immobilise the window; and PA1 of means for cutting out the frame which are carried by the central layer and which are driven by pulling on at least a part of the window perimeter in order to divide into two at least a section of the frame and thus disconnect the window from the support. PA1 the means of cutting out comprise a double blade consisting of a central part passed through by a first end of the wire, the height of the double blade being at least equal to the thickness of the joint central layer; PA1 the two blades are inclined rearward relative to their driving movement and the central part comprises a protuberance which is situated in front of the blades and which gives a punching effect during movement of the double blade; PA1 the internal edge of the joint includes a window reception groove and the external efge of the joint is thinned down in order to be adhered to the support, such that the window, the joint and the support form an approximately continuous and flat surface; and PA1 the wire comprises a second end passed into a means of reverse movement and fixed to a pulling handle, the means of return movement being fixed to the support, approximately vertically from the joint central layer.
In this document, the means of cutting out consist of a metal wire buried in the joint and extending over the whole perimeter of the window. A free end of the wire is fixed to a handle which can be grabbed by a passenger.
In order to release such a window, the passenger must pull on the handle along the window perimeter so that the metal wire can cut out the joint and thus disconnect the window from the structure.
However, the cutting out of the joint is not very easy insofar as the passenger must exert a force of great intensity.